1. Technical Field
The present disclosure relates to an analog front-end circuit for measurement suitable for use as, for example, a front end for a recorder or a temperature controller.
2. Related Art
A sensor signal processor (MAX1464) manufactured by Maxim Integrated Products is known as an example of the analog front-end circuit (Non-Patent Document 1: “Low-Power, Low-Noise Multichannel Sensor Signal Processor”, MAX1464 Data Sheet Rev 0, http://www.maximintegrated.com/datasheet/index.mvp/id/4590). MAX1464 is a low power and low noise multichannel sensor signal processor. This MAX1464 is often used for industrial, automotive, and process control applications such as pressure sensing/compensation, RTD (Resistance Temperature Detector)/thermocouple linearization, weight sensing/classification, and remote process monitoring with limit indication.
MAX1464 includes a MUX (Multiplexer), a PGA (Programmable Gain Amplifier), an ADC (Analog-Digital Converter), a CPU (Central Processing Unit), a DAC (Digital-Analog Converter), and a PWM (Pulse Width Modulator). MAX1464 having such a configuration operates, for example, as follows: Output from a sensor connected to MAX1464 is selected by the MUX and subjected to gain adjustment by the PGA. Subsequently, the sensor output is converted to a digital value by the ADC. The digital data obtained by the conversion is then computed by the CPU. The resulting data is output as a digital signal from the CPU to a system via a serial interface. Alternatively, the digital signal is converted to an analog signal by the DAC or to a pulse width modulation (PWM) signal by the PWM and then output.